1. Field of the Invention
The present invention relates to a low-temperature heat-shrinkable film having a high heat shrinkability and a large shrinkage stress at a low temperature, having an excellent transparency, and having a broad heat-sealing temperature range wherein a good heat-sealing strength is maintained. More particularly, the present invention relates to a low-temperature heat-shrinkable film which is valuable for use as shrinkable packaging film when a high temperature must not be applied to a material to be packaged, a large shrinkage stress is required for tightly binding a material to be packed, a transparency is required to allow a packaged material to be displayed or a heat sealing finish is desired.
2. Description of the Related Art
Conventional heat-shrinkable films, for example, heat-shrinkable films made of polyvinyl chloride or polypropylene usually begin to shrink at about 100.degree. C., and a shrinkage as large as 50 to 70% occurs at about 130.degree. C. Nevertheless, these heat-shrinkable films have a heat-sealing strength lower than that of a heat-shrinkable film made of polyethylene.
A high-pressure low-density polyethylene resin is usually used for a heat shrinkable film. The melting point of this resin is about 110.degree. C., and therefore, a film of this resin is disadvantageous when compared with heat-shrinkable films made of polyvinyl chloride or polypropylene, in that it is impossible to obtain a large shrinkage stress at a shrinking temperature of about 130.degree. C. and the binding force is not tight enough.